gleam/regex
This module contains regular expression matching functions for strings. The matching algorithms of the library are based on the PCRE library, but not all of the PCRE library is interfaced and some parts of the library go beyond what PCRE offers. Currently PCRE version 8.40 (release date 2017-01-11) is used.
Types
When a regular expression fails to compile:
pub type CompileError {
CompileError(error: String, byte_index: Int)
}
Constructors
-
CompileError(error: String, byte_index: Int)
Arguments
-
error
The problem encountered that caused the compilation to fail
-
byte_index
The byte index into the string to where the problem was found This value may not be correct in JavaScript environments.
-
The details about a particular match:
pub type Match {
Match(content: String, submatches: List(Option(String)))
}
Constructors
-
Match(content: String, submatches: List(Option(String)))
Arguments
-
content
The full string of the match.
-
submatches
A
Regex
can have subpatterns, sup-parts that are in parentheses.
-
pub type Options {
Options(case_insensitive: Bool, multi_line: Bool)
}
Constructors
-
Options(case_insensitive: Bool, multi_line: Bool)
Functions
pub fn check(with regex: Regex, content content: String) -> Bool
Returns a boolean indicating whether there was a match or not.
Examples
let assert Ok(re) = from_string("^f.o.?")
check(with: re, content: "foo")
// -> True
check(with: re, content: "boo")
// -> False
pub fn compile(
pattern: String,
with options: Options,
) -> Result(Regex, CompileError)
Creates a Regex
with some additional options.
Examples
let options = Options(case_insensitive: False, multi_line: True)
let assert Ok(re) = compile("^[0-9]", with: options)
check(re, "abc\n123")
// -> True
let options = Options(case_insensitive: True, multi_line: False)
let assert Ok(re) = compile("[A-Z]", with: options)
check(re, "abc123")
// -> True
pub fn from_string(
pattern: String,
) -> Result(Regex, CompileError)
Creates a new Regex
.
Examples
let assert Ok(re) = from_string("[0-9]")
check(re, "abc123")
// -> True
check(re, "abcxyz")
// -> False
from_string("[0-9")
// -> Error(CompileError(
// error: "missing terminating ] for character class",
// byte_index: 4
// ))
pub fn replace(
each pattern: Regex,
in string: String,
with substitute: String,
) -> String
Creates a new String
by replacing all substrings that match the regular
expression.
Examples
let assert OK(re) = regex.from_string("^https://")
replace(each: re, in: "https://example.com", with: "www.")
// -> "www.example.com"
let assert OK(re) = regex.from_string("[, +-]")
replace(each: re, in: "a,b-c d+e", with: "/")
// -> "a/b/c/d/e"
`
pub fn scan(
with regex: Regex,
content string: String,
) -> List(Match)
Collects all matches of the regular expression.
Examples
let assert Ok(re) = from_string("[oi]n a (\\w+)")
scan(with: re, content: "I am on a boat in a lake.")
// -> [
// Match(content: "on a boat", submatches: [Some("boat")]),
// Match(content: "in a lake", submatches: [Some("lake")]),
// ]
let assert Ok(re) = regex.from_string("([+|\\-])?(\\d+)(\\w+)?")
scan(with: re, content: "-36")
// -> [
// Match(content: "-36", submatches: [Some("-"), Some("36")])
// ]
scan(with: re, content: "36")
// -> [
// Match(content: "36", submatches: [None, Some("36")])
// ]
let assert Ok(re) =
regex.from_string("var\\s*(\\w+)\\s*(int|string)?\\s*=\\s*(.*)")
scan(with: re, content: "var age = 32")
// -> [
// Match(
// content: "var age = 32",
// submatches: [Some("age"), None, Some("32")],
// ),
// ]
let assert Ok(re) = regex.from_string("let (\\w+) = (\\w+)")
scan(with: re, content: "let age = 32")
// -> [
// Match(
// content: "let age = 32",
// submatches: [Some("age"), Some("32")],
// ),
// ]
scan(with: re, content: "const age = 32")
// -> []